The protocol of Montreal for the protection of the ozone layer led to the end of the use of chlorofluorocarbons (CFCs). Less aggressive compounds for the ozone layer, such as the hydrofluorocarbons (HFCs) e.g. HFC-134a replaced chlorofluorocarbons. These latter compounds were indeed shown to provide greenhouse gases. There exists a need for the development of technologies, which present a low ODE (ozone depletion potential) and a low GWP (global warming potential). Although the hvdrofluorocarbons (HFCs), which are compounds which do not affect the ozone layer, were identified as interesting candidates, they exhibit a relatively high GWP value. There still exists the need to find compounds which exhibit a low GWP value. Hydrofluoroolefins (HFO) were identified as being possible alternatives with very low ODE and OWE values.
Several processes for production of HFOs compounds, in particular of propenes, were developed. The two compounds 1233xf (2-chloro-3,3,3-trifluoropropene) and 1234yf (2,3,3,3-tetrafluoropropene) are particularly desired.
US2009/0240090 discloses the gas-phase reaction of 1,1,1,2,3-pentachloropropane (HCC 240db) into product 2-chloro-3,3,3-trifluoropropene (HCFO 1233xf) (in the absence of oxygen). The catalyst used in Example 3 is fluorinated Cr2O3. The product 1233xf thus produced is then converted into product 2-chloro-1,1,1,2-tetrafluoropropane (244bb) in a liquid phase reaction.
WO2009/015317 discloses the reaction of a chlorinated compound, which can be 1,1,2,3-tetrachloro-1-propene (1230xa), 1,1,1,2,3-pentachloropropane (240db) or 2,3,3,3-tetrachloro-1-propene (1230xf) with HF, in gas phase, on a catalyst and in the presence of at least one stabilizer. This process allows obtaining 2-Chloro-3,3,3-trifluoro-1-propene (1233xf). No working example is provided with 240db as a starting material. The stabilizer is said to improve catalyst lifetime. It is also mentioned that periodic regeneration is considered.
WO2005/108334, example 3, discloses that 240db is passed through a flow reactor for a contact time for about 5 to 50 seconds at about 250-400° C. in the presence of 5 molar excess of HF over a 50 g ⅛-inch Cr2O3 catalyst bed to give 244db (2-chloro-1,1,1,3-tetrafluoropropane). It is further indicated that the 244db is then dehydrochlorinated by passing it over a Cr2O3 catalyst (50 g) at 425-550° C. with a contact time of 25 to 30 seconds to afford product 1234ze (1,3,3,3-tetrafluoropropene).
GB-A-1091103 discloses a process for manufacturing a chromium fluorination catalyst. Numerous compounds that may be fluorinated using this catalyst are indicated: pentachloropropane is mentioned among others, while not being the preferred compound.
WO2010/123148 discloses the fluorination of 240db into 1293xf, in the absence of catalyst.
Thus, there is still a need for processes for the production of compound 1234yf.